1. Field of the Invention
The present invention relates to a positive pressure test apparatus and, more particularly, to a facepiece respirator including a positive pressure test apparatus.
2. Description of the Prior Art
Facepiece respirators are commonly used as protection against inhaling airborne contaminants. The airborne contaminants may be gaseous or liquid droplets or solid particulates entrained in a gas such as air. Dusts, paint spray, mist, fumes and gaseous organic solvents are examples of such substances. These respirators are either of the positive pressure type where clean air is forced under pressure into the respirator for breathing by the user, or the negative pressure type where the inhalation of the user draws ambient environment into the respirator for breathing. In the latter instance, the respirator is provided with means, such as one or more filter cartridges, which extract airborne contaminants from the environment as it is drawn into the respirator, thereby rendering the environment suitable for breathing. Both types of respirators utilize exhalation valves, which are one-way valves used to prevent airborne contaminants from entering the respirator as the user exhales.
Leakage of contaminated ambient environment into the respirator, such as between the peripheral edges of the respirator and the user's face, is a serious consideration. Such leakage defeats the purpose of the respirator and results in the user inhaling the contaminant.
Three agencies are involved with the control, regulation or recommendation as to the acceptable practice in regard to respirator protection. These agencies are the National Institute of Occupational Safety and Health (NIOSH), Occupational Safety and Health Administration (OSHA), and American Congress of Governmental Industrial Hygiene (ACGIH). NIOSH has the principal responsibility for testing and certifying respiratory protection equipment to include both face pieces, cartridges and assemblies testing. Criteria is established by NIOSH based upon extensive medical evaluation of exposure levels for occupational substances.
OSHA has been mandated by Congress to establish safe workplace conditions and to promulgate laws to enforce such conditions. OSHA has public hearings before promulgation of such occupational levels. Once the law has been instituted by Congress, OSHA is mandated to enforce the newly passed legislation. Traditionally OSHA has promulgated laws to reflect the permissible exposure levels (PEL's) which establishes the average conditions employees cannot exceed.
ACGIH is an agency which has established occupational exposure levels to hazardous substances in the workplace since the 1930's. ACGIH has been a consensus industry standard and generally has established "Ceiling Concentrations" and Threshold Limit Values (TLV's) which define concentration levels to which nearly every worker can be exposed without any deleterious health effect. Time Weighted Average (TWA), another related measurement of concentration, is used within the health discipline to refer to average concentration per limit of time, normally an eight hour work day.
Respirators are typically tested against the TWA and/or TLV of a particular hazardous substance to establish the efficiency of the respirator. Each respirator and filter combination is tested for typical airborne contaminants for which the respirator and filter are intended to be effective.
The effectiveness of the negative pressure type respirators is largely determined by the filters used, as well as the fit of the respirator on the user's face. Alternatively, because a positive pressure type respirator utilizes clean air forced under pressure into the respirator without filters, the primary factor in determining its effectiveness is the leakage allowable. Leakage of a respirator of the positive pressure type can be determined by the fit of the respirator to the face of the user. The term "leakage" refers to the passage of the ambient environment into the interior of the respirator. To aid in establishing an effective seal between the respirator and the user's face, the respirator is provided with a resilient peripheral rim for engaging the face, and is held in position by a series of adjustable straps. An initial fitting operation involves selecting an appropriately sized respirator, applying the respirator to the user, placing the user in a controlled challenge atmosphere, causing the user to breath, and capturing a portion of the gas from inside the respirator for analysis for the "challenge" substance. This process, or other suitable quantitative test, is repeated as many times as necessary, with intervening fit adjustments until an acceptable level of the challenge substance is detected within the respirator.
Typically, qualitative fit tests of facepiece respirators are performed to verify that the respirator has been applied properly to the face. The tests should be performed in uncontaminated air, immediately before entering the contaminated area. If any leakage is detected, the respirator must be readjusted until there is no leakage. The procedure involves temporarily covering the outlet openings to the exhalation valve with one or two hands, or with a piece of tape, plastic film, paper or the like, and exhaling into the mask. The mask will become slightly distended if the seal to the user's face is acceptable. The fit is satisfactory if the facepiece remains in the distended condition for a period of about ten seconds and no outward leakage of air is detected. While blocking the exhalation valve is an effective method to fit check facepiece respirators of the positive pressure type, it is noted that the procedure can be difficult for the user, particularly when the user is wearing safety gloves or other safety equipment or carrying tools or the like. A respirator user's hands may be too small to cover the exhalation valve completely, or a piece of tape, paper or the like may not be immediately available. Additionally, the user's hands or gloves may be contaminated with a material which could damage the respirator mask.
It is therefore an object of this invention to provide a positive pressure test apparatus which is easy to use, readily available and sanitary. It is a further object of this invention to provide a respirator including a facepiece and a positive pressure test apparatus mounted to the facepiece.